This invention relates to seals for fluid containers and, more particularly, to containers with open gaps having a wide gap tolerance and seals adapted therefor.
It is known in the art relating to fluid container seals that for long term life, a resilient seal material has a limited range of compression within which it may be expected to provide an effective seal over a maximum lifetime. If the seal is under compressed, its sealing effectiveness may be compromised. However, if the material is over compressed, conditions of beat and exposure to fluids such as oil, may significantly impact the ability of the seal to perform its intended function.
Designing seals for joints where two machined surfaces are maintained in direct engagement with one another is relatively simple. A groove is provided in one of the surfaces for receiving the seal, which is designed with a length of extension beyond the depth of the groove, so that upon engagement of the surfaces to be sealed, compression of the seal material will fall within the desired compression range for maximum life. However, in some applications of seals in fluid containers the tolerances of the components to be scaled together are too large to allow direct contact between the sealing surfaces.
One example is a rocker cover for an automotive engine wherein, for noise isolation purposes, the rocker cover and the associated cylinder head or manifold, have a gap by design between the sealed surfaces which varies significantly from a condition of maximum stack-up or tolerances creating a wider gap and a minimum stack-up or tolerances creating a smaller gap. This situation may be compounded by a limit on the depth of the groove, which is provided in one of the components for supporting a generally rectangular seal in the groove and extending therebeyond. If such a seal extends beyond the supporting portion of the groove by an excessive length, the unsupported portion of the seal will buckle when compressed, resulting in inadequate compression or rotating in the groove, which leads to unsatisfactory seal performance.
The present invention provides supplemental support by the addition of two symmetrical barb-like projections that make contact outside of the retaining groove for an otherwise unsupported rectangular portion of a seal that extends beyond the retaining groove formed in one member of a container assembly. By providing this supplemental support, the seal is able to be extended a greater distance so as to close a larger gap than would be possible with a typical rectangular seal configuration. Accordingly, larger differences in the stack up gap or tolerances of the assembly may be accommodated by a molded seal acting within its ideal limits of compression.
We have learned that with a conventional rectangular seal, the unsupported seal height beyond the groove should not be more than about 1.5 times the supported seal height within the groove. Otherwise, the seal will buckle when compressed unless some additional support is provided for the portion of the seal height which extends beyond the supporting length of the groove in which the seal is retained.
In a preferred embodiment, a seal according to the invention includes a linearly extending resilient seal body with a cross-sectional configuration including a generally rectangular central section of greater height than width and having first and second sealing edges at opposite ends of the height dimension. The central section includes first and second compressible portions extending inward from the first and second sealing edges and which represent the supported and unsupported portions of the seal.
Accordingly, the first compressible portion includes generally parallel sides which are adapted to be supported in a groove in a seal surface of one component of the assembly, wherein the first sealing edge engages the bottom of the groove for sealing the groove against fluid passage across the groove. The second compressible portion includes sides which carry resilient stabilizers, also of the same compressible material. The stabilizers are angled outward from the second sealing edge which is adapted to engage a flat surface of the other member of the container assembly. The stabilizers terminate in barb-like projections that are engageable with a flat portion of the grooved surface adjacent to the groove.
Upon compression of the seal, the stabilizers are compressed against the flat surface adjacent the groove of the grooved surface. The stabilizers are designed to resiliently yield as they provide support for the second compressible portion of the central section to prevent it from buckling while the seal is compressed to within its desired range of compression. The seal compression takes place over the entire seal height, from the first sealing edge engaging the bottom of the groove to the second sealing edge engaging the flat portion of the opposing surface of the joint.
An additional advantage of a seal according to the invention is that the resilient stabilizers, by their contact with the seal surface adjacent to the groove, help shield the seal against the entry of fluid or debris into the groove and thus help prolong seal life. This is especially advantageous when the seal groove is formed in a lower member of a container.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.